Semiconductor device and semiconductor circuit

ABSTRACT

According to an embodiment a semiconductor device includes a semiconductor layer including first trenches and second trenches, a first gate electrode in the first trench, a second gate electrode in the second trench, a first gate electrode pad, a second gate electrode pad, a first wiring connecting the first gate electrode pad and the first gate electrode, and a second wiring connecting the second gate electrode pad and the second gate electrode. The semiconductor layer includes a first connection trench. Two first trenches adjacent to each other are connected to each other at end portions by the first connection trench. At least one of the second trenches is provided between the two first trenches. The second gate electrode in the at least one second trench is electrically connected to the second wiring between the two first trenches.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/791,679 filed Feb. 14, 2020. U.S. application Ser. No. 16/791,679 isbased upon and claims the benefit of priority from Japanese PatentApplication No. 2019-171100, filed on Sep. 20, 2019, the entire contentsof which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor deviceand a semiconductor circuit.

BACKGROUND

An insulated gate bipolar transistor (IGBT) is one example of a powersemiconductor device. The IGBT has, for example, a p-type collectorregion, an n-type drift region, and a p-type base region on a collectorelectrode. A trench penetrates the p-type base region and reaches then-type drift region. A gate electrode exists in the trench. A gateinsulating film interposed between the gate electrode and the trench. Ann-type emitter region connected to an emitter electrode. The n-typeemitter region exists at the surface of the p-type base region. Then-type emitter region is adjacent to the trench.

In the IGBT, a channel is formed in the p-type base region by applying apositive voltage (equal to or greater than a threshold voltage) to thegate electrode. Holes are injected into the n-type drift region from thecollector region at the same time when electrons are injected into then-type drift region from the n-type emitter region. Thus, currents usingthe electrons and holes as carriers flows between the collectorelectrode and the emitter electrode.

In order to reduce the on-resistance of the IGBT, it is effective toincrease carrier concentration of the n-type drift region in an ONstate. If the discharge of the carriers in the n-type drift region isdelayed when the IGBT turns off, the turn-off time increases, and thusthe switching loss increases.

Double gate driving is proposed as a method for achieving both reductionof the on-resistance and reduction of the switching loss. Double gatedriving is a technology in which two gate driving system are used, andtwo gate driving timings are changed, and thus a switching time of theIGBT is reduced, and the switching loss is reduced. Accordingly, it ispossible to achieve both reduction of the on-resistance and reduction ofthe switching loss.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a semiconductor circuitaccording to a first embodiment;

FIG. 2 is a schematic diagram illustrating a semiconductor device in thefirst embodiment;

FIG. 3 is a cross-sectional view schematically illustrating a portion ofthe semiconductor device in the first embodiment;

FIG. 4 is a top view schematically illustrating the portion of thesemiconductor device in the first embodiment;

FIG. 5 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the first embodiment;

FIG. 6 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the first embodiment;

FIG. 7 is a schematic diagram illustrating a semiconductor deviceaccording to a second embodiment;

FIG. 8 is a cross-sectional view schematically illustrating a portion ofthe semiconductor device in the second embodiment;

FIG. 9 is a top view schematically illustrating the portion of thesemiconductor device in the second embodiment;

FIG. 10 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the second embodiment;

FIG. 11 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the second embodiment;

FIG. 12 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the second embodiment;

FIG. 13 is a schematic diagram illustrating a semiconductor deviceaccording to a third embodiment;

FIG. 14 is a top view schematically illustrating a portion of thesemiconductor device in the third embodiment;

FIG. 15 is a cross-sectional view schematically illustrating a portionof the semiconductor device in the third embodiment;

FIG. 16 is a cross-sectional view schematically illustrating a portionof a semiconductor device according to a fourth embodiment;

FIG. 17 is a cross-sectional view schematically illustrating a portionof the semiconductor device in the fourth embodiment;

FIG. 18 is a schematic diagram illustrating a semiconductor deviceaccording to a fifth embodiment;

FIG. 19 is a top view schematically illustrating a portion of thesemiconductor device in the fifth embodiment; and

FIG. 20 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the fifth embodiment.

DETAILED DESCRIPTION

According to an embodiment, a semiconductor device includes asemiconductor layer including a first plane and a second plane, thefirst plane being parallel to a first direction and a second directionperpendicular to the first direction, and the second plane facing thefirst plane, and the semiconductor layer including a first semiconductorregion having a first conductive type, a second semiconductor regionhaving a second conductive type and being provided between the firstsemiconductor region and the first plane, a third semiconductor regionhaving the first conductive type and being provided between the secondsemiconductor region and the first plane, a fourth semiconductor regionhaving the second conductive type and being provided between the thirdsemiconductor region and the first plane, a plurality of first trenchesextending in the first direction, being repetitively disposed in thesecond direction, and having a distance from the second plane, thedistance being smaller than a distance from the second plane to thethird semiconductor region, and a plurality of second trenches extendingin the first direction, being repetitively disposed in the seconddirection, and having a distance from the second plane, the distancebeing smaller than a distance from the second plane to the thirdsemiconductor region; a first gate electrode provided in each of thefirst trenches; a first gate insulating film provided between the firstgate electrode and the third semiconductor region and between the firstgate electrode and the fourth semiconductor region, the first gateinsulating film being in contact with the fourth semiconductor region; asecond gate electrode provided in each of the second trenches; a secondgate insulating film provided between the second gate electrode and thethird semiconductor region; a first electrode provided on the firstplane side of the semiconductor layer, the first electrode beingelectrically connected to the fourth semiconductor region; a secondelectrode provided on the second plane side of the semiconductor layer,the second electrode being electrically connected to the firstsemiconductor region; a first gate electrode pad provided on the firstplane side of the semiconductor layer, a first gate voltage beingapplied to the first gate electrode pad; a second gate electrode padprovided on the first plane side of the semiconductor layer, a secondgate voltage being applied to the second gate electrode pad; a firstwiring electrically connecting the first gate electrode pad and thefirst gate electrode; and a second wiring electrically connecting thesecond gate electrode pad and the second gate electrode, wherein thesemiconductor layer includes a first connection trench, two of the firsttrenches adjacent to each other are connected to each other at endportions by the first connection trench, at least one of the secondtrenches is provided between the two of the first trenches, and thesecond gate electrode in the at least one of the second trenches iselectrically connected to the second wiring at a first position betweenthe two of the first trenches.

Hereinafter, embodiments of the disclosure will be described withreference to the drawings. In the following descriptions, the same orsimilar members and the like are denoted by the same reference signs,and descriptions of a member which has been described once will beappropriately omitted.

In this specification, descriptions of an n⁺ type, an n-type, and an n⁻type mean that the n-type impurity concentration is reduced in order ofthe n⁺ type, the n-type, and the n⁻ type. Descriptions of a p⁺ type, ap-type, and a p⁻ type mean that the p-type impurity concentration isreduced in order of the p⁺ type, the p-type, and the p⁻ type.

In this specification, the distribution and the absolute value of theimpurity concentration in a semiconductor region may be measured, forexample, using secondary ion mass spectrometry (SIMS). The relativemagnitude relation in impurity concentration between two semiconductorregions may be determined, for example, using scanning capacitancemicroscopy (SCM). The distribution and the absolute value of theimpurity concentration may be measured, for example, using a spreadingresistance analysis (SRA). The relative magnitude relation and theabsolute value of the carrier concentration in the semiconductor regionare obtained by the SCM and the SRA. By assuming an activation rate ofimpurities, the relative magnitude relation in impurity concentrationbetween two semiconductor regions, the distribution of the impurityconcentration, and the absolute value of the impurity concentration maybe obtained from measurement results of the SCM and the SRA.

First Embodiment

According to a first embodiment, a semiconductor device includes asemiconductor layer including a first plane and a second plane, thefirst plane being parallel to a first direction and a second directionperpendicular to the first direction, and the second plane facing thefirst plane, and the semiconductor layer including a first semiconductorregion having a first conductive type, a second semiconductor regionhaving a second conductive type and being provided between the firstsemiconductor region and the first plane, a third semiconductor regionhaving the first conductive type and being provided between the secondsemiconductor region and the first plane, a fourth semiconductor regionhaving the second conductive type and being provided between the thirdsemiconductor region and the first plane, a plurality of first trenchesextending in the first direction, being repetitively disposed in thesecond direction, and having a distance from the second plane, thedistance being smaller than a distance from the second plane to thethird semiconductor region, and a plurality of second trenches extendingin the first direction, being repetitively disposed in the seconddirection, and having a distance from the second plane, the distancebeing smaller than a distance from the second plane to the thirdsemiconductor region; a first gate electrode provided in each of thefirst trenches; a first gate insulating film provided between the firstgate electrode and the third semiconductor region and between the firstgate electrode and the fourth semiconductor region, the first gateinsulating film being in contact with the fourth semiconductor region; asecond gate electrode provided in each of the second trenches; a secondgate insulating film provided between the second gate electrode and thethird semiconductor region; a first electrode provided on the firstplane side of the semiconductor layer, the first electrode beingelectrically connected to the fourth semiconductor region; a secondelectrode provided on the second plane side of the semiconductor layer,the second electrode being electrically connected to the firstsemiconductor region; a first gate electrode pad provided on the firstplane side of the semiconductor layer, a first gate voltage beingapplied to the first gate electrode pad; a second gate electrode padprovided on the first plane side of the semiconductor layer, a secondgate voltage being applied to the second gate electrode pad; a firstwiring electrically connecting the first gate electrode pad and thefirst gate electrode; and a second wiring electrically connecting thesecond gate electrode pad and the second gate electrode, wherein thesemiconductor layer includes a first connection trench, two of the firsttrenches adjacent to each other are connected to each other at endportions by the first connection trench, at least one of the secondtrenches is provided between the two of the first trenches, and thesecond gate electrode in the at least one of the second trenches iselectrically connected to the second wiring at a first position betweenthe two of the first trenches.

According to the first embodiment, a semiconductor circuit includes thesemiconductor device and a control circuit configured to drive thesemiconductor device and to change the second gate voltage from a firstvoltage to a second voltage before the first gate voltage is changedfrom a turn-on voltage to a turn-off voltage, the second voltage being anegative voltage when the first conductive type is a p-type and being apositive voltage when the first conductive type is an n-type.

According to the first embodiment, the semiconductor circuit includesthe semiconductor device and the control circuit that controls thesemiconductor device.

FIG. 1 is a schematic diagram illustrating the semiconductor circuitaccording to the first embodiment. In the first embodiment, thesemiconductor circuit includes an IGBT 100 and a gate driver circuit150. The IGBT 100 is an example of the semiconductor device. The gatedriver circuit 150 is an example of the control circuit.

The IGBT 100 is a trench gate type IGBT including a gate electrode in atrench formed in a semiconductor layer. The IGBT 100 is capable ofdouble gate driving. A case where the first conductive type is a p-type,and the second conductive type is an n-type will be described below asan example.

The IGBT 100 includes a cell region 101, a cell end region 102, atermination region 103, a main gate electrode pad (first gate electrodepad) 111, and a control gate electrode pad (second gate electrode pad)112.

The cell end region 102 is provided around the cell region 101. The cellend region 102 is provided to be adjacent to the cell region 101. Thetermination region 103 is provided around the cell region 101 and thecell end region 102.

The cell region 101 has the main function of causing a current to flowwhen the IGBT 100 is in an ON state. The cell end region 102 has afunction of reducing current concentration when the IGBT 100 performs aturn-off operation. The cell end region 102 has, for example, astructure of electrically connecting a main gate electrode 51 in thecell region 101 to the main gate electrode pad 111 or electricallyconnecting a control gate electrode 52 in the cell region 101 to thecontrol gate electrode pad 112. The termination region 103 has afunction of suppressing a decrease in a breakdown voltage of the IGBT100 when the IGBT 100 is in an OFF state, that is, is reversely biased.For example, a guard ring (not illustrated) is provided in thetermination region 103.

FIG. 2 is a schematic diagram illustrating the semiconductor device inthe first embodiment. FIG. 2 illustrates a positional relation and aconnection relation between the first trench, the second trench, thefirst gate electrode pad, the second gate electrode pad, the firstwiring, and the second wiring.

FIG. 3 is a cross-sectional view schematically illustrating a portion ofthe semiconductor device in the first embodiment. FIG. 4 is a top viewschematically illustrating the portion of the semiconductor device inthe first embodiment. FIG. 5 is a cross-sectional view schematicallyillustrating the portion of the semiconductor device in the firstembodiment. FIG. 6 is a cross-sectional view schematically illustratingthe portion of the semiconductor device in the first embodiment.

FIGS. 3 to 6 are enlarged view illustrating a region R surrounded by adotted frame in FIG. 2. The region R includes a boundary region betweenthe cell region 101 and the cell end region 102.

FIG. 3 illustrates a cross-section taken long line AA′ in FIG. 4. FIG. 3illustrates a cross-section of the cell region 101.

FIG. 5 illustrates a cross-section taken long line BB′ in FIG. 4. FIG. 5illustrates a cross-section of the cell end region 102.

FIG. 6 illustrates a cross-section taken long line CC′ in FIG. 4. FIG. 6illustrates a cross-section of the cell region 101 and the cell endregion 102.

FIGS. 2 and 4 are top views illustrating a first plane P1 of thesemiconductor layer 10.

In the first embodiment, the IGBT 100 includes a semiconductor layer 10,an emitter electrode (first electrode) 12, a collector electrode (secondelectrode) 14, a main gate insulating film (first gate insulating film)41, a control gate insulating film (second gate insulating film) 42, adummy gate insulating film 43, a main gate electrode (first gateelectrode) 51, a control gate electrode (second gate electrode) 52, adummy gate electrode 53, an interlayer insulating layer 60, a contactplug (conductive layer) 70, a main gate electrode pad (first gateelectrode pad) 111, a control gate electrode pad (second gate electrodepad) 112, a main gate wiring (first wiring) 121, and a control gatewiring (second wiring) 122.

In the semiconductor layer 10, a main gate trench (first trench) 21, acontrol gate trench (second trench) 22, a dummy gate trench 23, a firstconnection trench 24, a collector region (first semiconductor region)28, a buffer region 30, a drift region (second semiconductor region) 32,a barrier region 33, a base region (third semiconductor region) 34, anemitter region (fourth semiconductor region) 36, a collector region 38,and a deep region (fifth semiconductor region) 39 are provided.

The semiconductor layer 10 includes the first plane P1 and a secondplane P2 facing the first plane P1. The semiconductor layer 10 is madeof single crystal silicon, for example.

In this specification, a direction parallel to the first plane P1 isreferred to as a first direction. A direction which is parallel to thefirst plane P1 and is perpendicular to the first direction is referredto as a second direction. A normal direction of the first plane P1 isreferred to as a third direction. In this specification, “a depth” isdefined as a distance in the third direction using the first plane P1 asa reference.

The emitter electrode 12 is provided on the first plane P1 side of thesemiconductor layer 10. At least a portion of the emitter electrode 12is in contact with the first plane P1 of the semiconductor layer 10. Theemitter electrode 12 is made of metal, for example.

The emitter electrode 12 is electrically connected to the emitter region36 and the collector region 38. An emitter voltage is applied to theemitter electrode 12. The emitter voltage is 0 V, for example.

The collector electrode 14 is provided on the second plane P2 side ofthe semiconductor layer 10. At least a portion of the collectorelectrode 14 is in contact with the second plane P2 of the semiconductorlayer 10. The collector electrode 14 is made of metal, for example.

The collector electrode 14 is electrically connected to the p-typecollector region 28. A collector voltage is applied to the collectorelectrode 14. The collector voltage is, for example, equal to or greaterthan 200 V and equal to or smaller than 6500 V.

The collector region 28 is a p-type semiconductor region. The collectorregion 28 is electrically connected to the collector electrode 14. Thecollector region 28 is in contact with the collector electrode 14.

The collector region 28 functions as a supply source of holes when theIGBT 100 is in the ON state.

The buffer region 30 is an n-type semiconductor region. The bufferregion 30 is provided between the collector region 28 and the firstplane P1. The buffer region 30 has a function of suppressing extensionof a depletion layer when the IGBT 100 is in the OFF state. Aconfiguration in which the buffer region 30 is not provided may be made.

The drift region 32 is an n⁻ type semiconductor region. The drift region32 is provided between the collector region 28 and the first plane P1.The drift region 32 is provided between the buffer region 30 and thefirst plane P1. The n-type impurity concentration of the drift region 32is lower than the n-type impurity concentration of the buffer region 30.

The drift region 32 functions as a path of an on-current when the IGBT100 is in the ON state. The drift region 32 has a function of depletingwhen the IGBT 100 is in the OFF state and maintaining the breakdownvoltage of the IGBT 100.

The barrier region 33 is an n-type semiconductor region. The barrierregion 33 is provided between the drift region 32 and the first planeP1. The barrier region 33 is provided between the drift region 32 andthe base region 34. The n-type impurity concentration of the barrierregion 33 is higher than the n-type impurity concentration of the driftregion 32.

Since the barrier region 33 having the n-type impurity concentrationhigher than the n-type impurity concentration of the drift region 32 isprovided on the first plane P1 side, the discharge of holes in the driftregion 32 to the emitter electrode 12 when the IGBT 100 is in the ONstate is restricted. Thus, the carrier concentration on the first planeP1 side of the drift region increases. Accordingly, the barrier region33 has a function of reducing the on-resistance of the IGBT 100.

The drift region 32 and the barrier region 33 are similarly n-typeimpurity regions. The n-type impurity concentration continuouslyincreases from the drift region 32 toward the barrier region 33.

A configuration in which the barrier region 33 is not provided may bemade.

The base region 34 is a p-type semiconductor region. The base region 34is provided between the drift region 32 and the first plane P1. The baseregion 34 is provided between the barrier region 33 and the first planeP1.

An inversion layer is formed in a region of the base region 34, whichfaces the main gate electrode 51, when the IGBT 100 is in the ON state.The base region 34 has a function as a channel region of a transistor.

The emitter region 36 is an n⁺ type semiconductor region. The emitterregion 36 is provided between the base region 34 and the first plane P1.The emitter region 36 extends in the first direction in the first planeP1.

The emitter region 36 is in contact with the main gate insulating film41. The emitter region 36 is spaced from the control gate insulatingfilm 42. The emitter region 36 is not in contact with the control gateinsulating film 42. The n-type impurity concentration of the emitterregion 36 is higher than the n-type impurity concentration of the driftregion 32.

The emitter region 36 is electrically connected to the emitter electrode12. The emitter region 36 is in contact with the emitter electrode 12.The emitter region 36 functions as a supply source of electrons when atransistor including the main gate electrode 51 is in the ON state.

The collector region 38 is a p⁺ type semiconductor region. The collectorregion 38 is provided between the base region 34 and the first plane P1.The collector region 38 extends in the first direction in the firstplane P1. The collector region 38 is electrically connected to theemitter electrode 12.

The deep region 39 is a p-type semiconductor region. The deep region 39is provided between the drift region 32 and the first plane P1. Thedepth of the deep region 39 is deeper than the depth of the base region34. The depth of the deep region 39 is deeper than the depths of themain gate trench 21, the control gate trench 22, and the dummy gatetrench 23, for example.

The deep region 39 is provided in the cell end region 102 or thetermination region 103. The deep region 39 has, for example, a functionof reducing electric field strength of the cell end region 102 or thetermination region 103.

The deep region 39 is provided between the first connection trench 24and the drift region 32. The deep region 39 is provided just under thefirst connection trench 24.

As illustrated in FIG. 2, the main gate trench 21 extends in the firstdirection parallel to the first plane P1, in the first plane P1. Themain gate trench 21 has a stripe shape. A plurality of main gatetrenches 21 are repetitively disposed in the second directionperpendicular to the first direction. The main gate trench 21 is agroove formed in the semiconductor layer 10.

The main gate trench 21 penetrates the base region 34 and the barrierregion 33 and then reaches the drift region 32. A distance of the maingate trench 21 from the second plane P2 is smaller than a distance fromthe second plane P2 to the base region 34.

As illustrated in FIG. 2, two main gate trenches 21 which are adjacentto each other and are selected from the main gate trenches 21 areconnected to each other at both end portions of the main gate trenchesby the first connection trench 24. For example, as illustrated in FIG.4, a main gate trench 21 a and a main gate trench 21 b are connected toeach other by the first connection trench 24 in the region R includingthe end portion of the cell region 101 in the first direction. The maingate trench 21 a and the main gate trench 21 b are similarly connectedto each other at the end portion of the cell region 101 on an oppositeside of the first direction, by the first connection trench 24.

A ring-like trench is formed by the main gate trench 21 a, the main gatetrench 21 b, and the first connection trench 24. Since both end portionsof the two main gate trenches 21 adjacent to each other are connected toeach other, the electric field strength at the end portion of the maingate trench 21 is reduced, and a gate insulating breakdown voltage ofthe IGBT 100 is increased.

The main gate electrode 51 is provided in the main gate trench 21. Themain gate electrode 51 is made of a semiconductor or metal, for example.The main gate electrode 51 is made of amorphous silicon orpolycrystalline silicon containing n-type impurities or p-typeimpurities, for example. The main gate electrode 51 is electricallyconnected to the main gate electrode pad 111.

The main gate insulating film 41 is provided between the main gateelectrode 51 and the semiconductor layer 10. The main gate insulatingfilm 41 is provided between the main gate electrode 51 and the driftregion 32, between the main gate electrode 51 and the barrier region 33,between the main gate electrode 51 and the base region 34, and betweenthe main gate electrode 51 and the emitter region 36. The main gateinsulating film 41 is in contact with the drift region 32, the barrierregion 33, the base region 34, and the emitter region 36. The main gateinsulating film 41 is made of silicon oxide, for example.

As illustrated in FIG. 2, the control gate trench 22 extends in thefirst direction parallel to the first plane P1, in the first plane P1.The control gate trench 22 has a stripe shape. A plurality of controlgate trenches 22 are repetitively disposed in the second directionperpendicular to the first direction. The control gate trench 22 is agroove formed in the semiconductor layer 10.

The control gate trench 22 penetrates the base region 34 and the barrierregion 33 and then reaches the drift region 32. A distance of thecontrol gate trench 22 from the second plane P2 is smaller than thedistance from the second plane P2 to the base region 34.

As illustrated in FIG. 2, at least one of the control gate trenches 22is provided between two main gate trenches 21 which are adjacent to eachother and have end portions connected to each other. For example, asillustrated in FIG. 4, a control gate trench 22 a is provided betweenthe main gate trench 21 a and the main gate trench 21 b having the endportions connected to each other, in the region R. The control gatetrench 22 a is surrounded by the ring-like trench including the maingate trench 21 a and the main gate trench 21 b.

The control gate electrode 52 is provided in the control gate trench 22.The control gate electrode 52 is made of a semiconductor or metal, forexample. The control gate electrode 52 is made of amorphous silicon orpolycrystalline silicon containing n-type impurities or p-typeimpurities, for example. The control gate electrode 52 is electricallyconnected to the control gate electrode pad 112.

The control gate insulating film 42 is provided between the control gateelectrode 52 and the semiconductor layer 10. The control gate insulatingfilm 42 is provided between the control gate electrode 52 and the driftregion 32, between the control gate electrode 52 and the barrier region33, between the control gate electrode 52 and the base region 34, andbetween the control gate electrode 52 and the collector region 38. Thecontrol gate insulating film 42 is in contact with the drift region 32,the barrier region 33, and the base region 34. The control gateinsulating film 42 is not in contact with the emitter region 36. Thecontrol gate insulating film 42 is spaced from the emitter region 36.The control gate insulating film 42 is made of silicon oxide, forexample.

A configuration in which the control gate insulating film 42 is incontact with the emitter region 36 provided between the main gate trench21 and the control gate trench 22 may be made.

As illustrated in FIG. 2, regarding a ratio of the number of controlgate trenches 22 to the number of main gate trenches 21, the ratio inthe cell end region 102 (first region) on the main gate electrode pad111 side and the cell end region 102 (second region) on the control gateelectrode pad 112 side located in the second direction of the cell endregion 102 on the main gate electrode pad 111 side is greater than theratio in the cell region 101 (third region). The cell region 101 isinterposed between the cell end region 102 on the main gate electrodepad 111 side and the cell end region 102 on the control gate electrodepad 112 side. In other words, the ratio of the number of control gatetrenches 22 to the number of main gate trenches 21 in the cell endregion 102 is greater than the ratio in the cell region 101. Manycontrol gate trenches 22 and control gate electrodes 52 are disposed inthe cell end region 102 in comparison to the cell region 101.

As illustrated in FIG. 2, the dummy gate trench 23 extends in the firstdirection parallel to the first plane P1, in the first plane P1. Thedummy gate trench 23 has a stripe shape. A plurality of dummy gatetrenches 23 are repetitively disposed in the second directionperpendicular to the first direction. The dummy gate trench 23 is agroove formed in the semiconductor layer 10.

The dummy gate trench 23 penetrates the base region 34 and the barrierregion 33 and then reaches the drift region 32. A distance of the dummygate trench 23 from the second plane P2 is smaller than the distancefrom the second plane P2 to the base region 34.

The dummy gate electrode 53 is provided in the dummy gate trench 23. Thedummy gate electrode 53 is made of a semiconductor or metal, forexample. The dummy gate electrode 53 is made of amorphous silicon orpolycrystalline silicon containing n-type impurities or p-typeimpurities, for example. The dummy gate electrode 53 is electricallyconnected to the emitter electrode 12.

The dummy gate insulating film 43 is provided between the dummy gateelectrode 53 and the semiconductor layer 10. The dummy gate insulatingfilm 43 is made of silicon oxide, for example.

A configuration in which the dummy gate trench 23, the dummy gateelectrode 53, and the dummy gate insulating film 43 are not provided maybe made.

The interlayer insulating layer 60 electrically separates the main gateelectrode 51 and the emitter electrode 12 from each other andelectrically separates the control gate electrode 52 and the emitterelectrode 12 from each other, for example. The interlayer insulatinglayer 60 is made of silicon oxide, for example.

The main gate electrode pad 111 is provided on the first plane P1 sideof the semiconductor layer 10. The main gate electrode pad 111 iselectrically connected to the main gate electrode 51. A first gatevoltage (Vg1) is applied to the main gate electrode pad 111.

The main gate wiring 121 electrically connects the main gate electrodepad 111 and the main gate electrode 51 to each other. The main gatewiring 121 is made of metal or an aluminum alloy, for example.

The main gate electrode 51 is connected to the main gate wiring 121 atan end portion of the main gate electrode 51 in the first direction. Themain gate electrode 51 is connected to the main gate wiring 121 at anend portion of the main gate electrode 51 in an opposite direction ofthe first direction. The main gate electrode 51 is connected to the maingate wiring 121 at both end portions.

In FIG. 2, black circles on the main gate wiring 121 indicate positionsat which the main gate wiring 121 is connected to the main gateelectrode 51. For example, the main gate wiring 121 is connected to themain gate electrode 51 at a position (third position) Y1 in FIG. 2. Theposition Y1 corresponds to the end portion of the main gate electrode 51in the first direction. For example, the main gate wiring 121 isconnected to the main gate electrode 51 at a position (fourth position)Y2 in FIG. 2. The position Y2 corresponds to the end portion of the maingate electrode 51 in the opposite direction of the first direction.

The main gate wiring 121 is connected to the main gate electrode 51 onboth the sides of the main gate trench 21 in the first direction and theopposite direction of the first direction.

As illustrated in FIG. 6, the main gate electrode 51 in the firstconnection trench 24 includes a lead region 51 a. The lead region 51 ais provided on the first plane P1. The main gate wiring 121 is incontact with the lead region 51 a at the position (third position) Y1.

The control gate electrode pad 112 is provided on the first plane P1side of the semiconductor layer 10. The control gate electrode pad 112is electrically connected to the control gate electrode 52. The controlgate wiring 122 is electrically connected to the control gate electrodepad 112 and the control gate electrode 52. A second gate voltage (Vg2)is applied to the control gate electrode pad 112.

The control gate wiring 122 electrically connects the control gateelectrode pad 112 and the control gate electrode 52 to each other. Thecontrol gate wiring 122 is made of metal or an aluminum alloy, forexample.

The control gate electrode 52 is connected to the control gate wiring122 at an end portion of the control gate electrode 52 in the firstdirection. The control gate electrode 52 is connected to the controlgate wiring 122 at an end portion of the control gate electrode 52 inthe opposite direction of the first direction.

In FIG. 2, black circles on the control gate wiring 122 indicatepositions at which the control gate wiring 122 is connected to thecontrol gate electrode 52. The control gate electrode 52 between twomain gate trenches 21 is connected to the control gate wiring 122 at aposition between the two main gate trenches 21.

The control gate wiring 122 is connected to the control gate electrode52 at a position (first position) X1 in FIG. 2, for example. Theposition X1 corresponds to the end portion of the control gate electrode52 in the first direction. The control gate wiring 122 is connected tothe control gate electrode 52 at a position (second position) X2 in FIG.2, for example. The position X2 corresponds to the end portion of thecontrol gate electrode 52 in the opposite direction of the firstdirection.

When the width of the control gate trench 22 in a directionperpendicular to the first direction is set as W1, a distance betweenthe position X1 and the end of the control gate trench 22 in the firstdirection is equal to or smaller than 30 times the width W1, forexample. When the width of the control gate trench 22 in a directionperpendicular to the first direction is set as W1, a distance betweenthe position X2 and the end of the control gate trench 22 in theopposite direction of the first direction is equal to or smaller than 30times the width W1, for example. The position X1 and the position X2 aremore preferably provided at the end (end portion) of the control gateelectrode 52 (as much as possible) in the first direction of the controlgate trench 22 and the opposite direction of the first direction.

The deep region 39 is provided between the position X1 and the driftregion 32. The deep region 39 is provided between the control gatetrench 22 just under the position X1 and the drift region 32. The deepregion 39 is provided between the contact plug 70 and the drift region32.

The deep region 39 is provided between the position X2 and the driftregion 32. The deep region 39 is provided between the control gatetrench 22 just under the position X2 and the drift region 32.

As illustrated in FIG. 4, for example, the control gate electrode 52 inthe control gate trench 22 a is connected to the control gate wiring 122at the position X1 between the main gate trench 21 a and the main gatetrench 21 b. The position X1 is a position at which the control gatewiring 122 intersects with the control gate trench 22 a.

As illustrated in FIGS. 5 and 6, the control gate wiring 122 isconnected to the control gate electrode 52 in the control gate trench 22a by using the contact plug 70. For example, the contact plug 70 isformed by burying a hole provided in the interlayer insulating layer 60on the control gate electrode 52.

The material of the contact plug 70 is different from the material ofthe control gate wiring 122, for example. As the material of the contactplug 70, for example, a material having burying ability for a small holebetter than the material of the control gate wiring 122 is used. Forexample, the material of the control gate wiring 122 is an aluminumalloy, and the material of the contact plug 70 is tungsten.

The contact plug 70 is in contact with the control gate electrode 52.The contact plug 70 is in contact with the control gate wiring 122.

The width (w1 in FIG. 5) of the contact plug 70 in the second directionis smaller than the width (w2 in FIG. 5) of the control gate electrode52 in the second direction.

The control gate wiring 122 intersects with the main gate trench 21.

The gate driver circuit 150 is provided in the same module as the IGBT100 or provided on the same circuit board as the IGBT 100. The gatedriver circuit 150 has a function of driving the IGBT 100.

The gate driver circuit 150 has a function of applying the desired firstgate voltage (Vg1) and the desired second gate voltage (Vg2) to the maingate electrode pad 111 and the control gate electrode pad 112 at adesired timing.

The gate driver circuit 150 changes the second gate voltage (Vg2) from afirst voltage to a second voltage before changing the first gate voltage(Vg1) from a turn-on voltage to a turn-off voltage. The second voltageis a negative voltage when the first conductive type is a p-type and isa positive voltage when the first conductive type is an n-type.

Next, the actions and effects of the semiconductor device in the firstembodiment will be described.

In order to reduce the on-resistance of the IGBT, it is effective toincrease carrier concentration of the drift region in the ON state. Ifthe discharge of the carriers from the drift region is delayed when theIGBT turns off, the turn-off time increases, and thus the switching lossincreases. Accordingly, it is desired to achieve both reduction of theon-resistance and reduction of the switching loss.

In the first embodiment, the IGBT 100 includes the main gate electrode51 in the main gate trench 21 and the control gate electrode 52 in thecontrol gate trench 22. The first gate voltage (Vg1) to be applied tothe main gate electrode 51 and the second gate voltage (Vg2) to beapplied to the control gate electrode 52 are independently controlled.

The IGBT 100 causes the second gate voltage (Vg2) to be the negativevoltage before changing the first gate voltage (Vg1) from the turn-onvoltage (Von) to the turn-off voltage (Voff). Since the second gatevoltage (Vg2) is set to be the negative voltage, a p-type inversionlayer is formed in the drift region 32 in contact with the control gateinsulating film 42 and the barrier region 33 in contact with the controlgate insulating film 42 (the drift region 32 and the barrier region 33face the control gate electrode 52).

Since the second gate voltage (Vg2) is set to be the negative voltage,it is possible to form the p-type inversion layer in the barrier region33 having the n-type impurity concentration higher than the n-typeimpurity concentration of the drift region 32.

Holes in the drift region 32 pass in the p-type inversion layer and aredischarged to the emitter electrode 12. Thus, the accumulated amount ofthe carrier on the first plane P1 side of the drift region 32 isreduced.

When the first gate voltage (Vg1) is changed from the turn-on voltage(Von) to the turn-off voltage (Voff), the accumulated amount of thecarrier on the first plane P1 side of the drift region 32 has beenalready reduced. Thus, the turn-off time becomes short. Thus, it ispossible to reduce the switching loss of the IGBT 100.

Since the control gate electrode 52 is provided in addition to the maingate electrode 51, in the IGBT 100, the control gate electrode pad 112and the control gate electrode 52 are connected to each other by thecontrol gate wiring 122. A connection between the control gate electrode52 and the control gate wiring 122 is performed in the cell end region102.

In the IGBT 100 in the first embodiment, the control gate electrode 52and the control gate wiring 122 are connected to each other at aposition between the two main gate trenches 21 adjacent to each other.With such a configuration, the restriction on the connection positionbetween the control gate electrode 52 and the control gate wiring 122 isreduced. Accordingly, the degree of freedom in pattern design of theIGBT 100 increases.

With the above configuration, it is possible to reduce the area requiredfor the connection between the control gate electrode 52 and the controlgate wiring 122. Accordingly, it is possible to reduce a chip area ofthe IGBT 100.

From a viewpoint of reducing a signal delay of the control gateelectrode 52, the control gate electrode 52 is preferably connected tothe control gate wiring 122 at both end portions.

In the IGBT 100 in the first embodiment, many control gate electrodes 52are disposed in the cell end region 102 in comparison to the cell region101. Thus, a hole extraction effect by the control gate electrode 52when the IGBT 100 turns off is enhanced in the cell end region 102.Accordingly, it is possible to suppress an occurrence of a situation inwhich a current concentrates on the vicinity of the main gate trench 21at the end portion of the cell region 101, and thus the IGBT 100 isbroken. Thus, reliability of the IGBT 100 is improved.

According to the first embodiment, it is possible to reduce theon-resistance of the IGBT and to reduce the switching loss. The degreeof freedom in pattern design of the IGBT increases. It is possible toreduce the chip area of the IGBT. An operation speed of the IGBT isincreased. The reliability of the IGBT is improved.

Second Embodiment

A semiconductor device according to a second embodiment is differentfrom the semiconductor device in the first embodiment in that thesemiconductor layer includes a second connection trench, and at leastone second trench and a second trench adjacent to the at least onesecond trench are connected to each other at end portions by the secondconnection trench. Some of descriptions of contents similar to thecontents in the first embodiment will be omitted below.

The semiconductor device in the second embodiment is an IGBT 200. TheIGBT 200 is a trench gate type IGBT including a gate electrode in atrench formed in a semiconductor layer. The IGBT 200 is capable ofdouble gate driving.

FIG. 7 is a schematic diagram illustrating the semiconductor device inthe second embodiment. FIG. 7 illustrates a positional relation and aconnection relation between the first trench, the second trench, thefirst gate electrode pad, the second gate electrode pad, the firstwiring, and the second wiring.

FIG. 8 is a cross-sectional view schematically illustrating a portion ofthe semiconductor device in the second embodiment. FIG. 9 is a top viewschematically illustrating the portion of the semiconductor device inthe second embodiment. FIG. 10 is a cross-sectional view schematicallyillustrating the portion of the semiconductor device in the secondembodiment. FIG. 11 is a cross-sectional view schematically illustratingthe portion of the semiconductor device in the second embodiment. FIG.12 is a cross-sectional view schematically illustrating the portion ofthe semiconductor device in the second embodiment.

FIGS. 8 to 12 are enlarged view illustrating a region R surrounded by adotted frame in FIG. 7. The region R is a boundary region between thecell region 101 and the cell end region 102.

FIG. 8 illustrates a cross-section taken long line DD′ in FIG. 9. FIG. 8illustrates a cross-section of the cell region 101.

FIG. 10 illustrates a cross-section taken long line EE′ in FIG. 9. FIG.10 illustrates a cross-section of the cell end region 102.

FIG. 11 illustrates a cross-section taken long line FF′ in FIG. 9. FIG.11 illustrates a cross-section of the cell region 101 and the cell endregion 102.

FIG. 12 illustrates a cross-section taken long line GG′ in FIG. 9. FIG.12 illustrates a cross-section of the cell region 101 and the cell endregion 102.

A second connection trench 25 is provided in the semiconductor layer 10.

As illustrated in FIG. 7, two control gate trenches 22 adjacent to eachother are connected to each other at both end portions by the secondconnection trench 25. For example, as illustrated in FIG. 9, a controlgate trench 22 a and a control gate trench 22 b are connected to eachother by the second connection trench 25 in the region R including theend portion of the cell region 101 in the first direction. The controlgate trench 22 a and the control gate trench 22 b are similarlyconnected to each other at the end portion of the cell region 101 on anopposite side of the first direction, by the second connection trench25.

The main gate electrode 51 is connected to the main gate wiring 121 atan end portion of the main gate electrode 51 in the first direction. Themain gate electrode 51 is connected to the main gate wiring 121 at anend portion of the main gate electrode 51 in an opposite direction ofthe first direction. The main gate electrode 51 is connected to the maingate wiring 121 at both end portions.

In FIG. 7, black circles on the main gate wiring 121 indicate positionsat which the main gate wiring 121 is connected to the main gateelectrode 51. For example, the main gate wiring 121 is connected to themain gate electrode 51 at a position (third position) Y1 in FIG. 7. Theposition Y1 corresponds to the end portion of the main gate electrode 51in the first direction. For example, the main gate wiring 121 isconnected to the main gate electrode 51 at a position (fourth position)Y2 in FIG. 7. The position Y2 corresponds to the end portion of the maingate electrode 51 in the opposite direction of the first direction.

The main gate wiring 121 is connected to the main gate electrode 51 onboth the sides of the main gate trench 21 in the first direction and theopposite direction of the first direction.

As illustrated in FIG. 12, the main gate electrode 51 in the firstconnection trench 24 includes a lead region 51 a. The lead region 51 ais provided on the first plane P1. The main gate wiring 121 is incontact with the lead region 51 a at the position (third position) Y1.

The control gate electrode 52 is connected to the control gate wiring122 at an end portion of the control gate electrode 52 in the firstdirection. The control gate electrode 52 is connected to the controlgate wiring 122 at an end portion of the control gate electrode 52 inthe opposite direction of the first direction.

In FIG. 7, black circles on the control gate wiring 122 indicatepositions at which the control gate wiring 122 is connected to thecontrol gate electrode 52. The control gate electrode 52 in the controlgate trench 22 between two main gate trenches 21 is connected to thecontrol gate wiring 122 at a position between the two main gate trenches21.

The control gate wiring 122 is connected to the control gate electrode52 at a position (first position) X1 in FIG. 7, for example. Theposition X1 corresponds to the end portion of the control gate electrode52 in the first direction. The control gate wiring 122 is connected tothe control gate electrode 52 at a position (second position) X2 in FIG.7, for example. The position X2 corresponds to the end portion of thecontrol gate electrode 52 in the opposite direction of the firstdirection.

As illustrated in FIG. 9, for example, the control gate electrode 52 inthe control gate trench 22 a is connected to the control gate wiring 122at the position X1 between the main gate trench 21 a and the main gatetrench 21 b. The position X1 is a position at which the control gatewiring 122 intersects with the control gate trench 22 a.

As illustrated in FIGS. 10 and 11, the control gate wiring 122 isconnected to the control gate electrode 52 in the control gate trench 22a by using the contact plug 70. For example, the contact plug 70 isformed by burying a hole provided in the interlayer insulating layer 60on the control gate electrode 52.

The material of the contact plug 70 is different from the material ofthe control gate wiring 122, for example. As the material of the contactplug 70, a material having burying ability for a small hole better thanthe material of the control gate wiring 122 is used. For example, thematerial of the control gate wiring 122 is an aluminum alloy, and thematerial of the contact plug 70 is tungsten.

The contact plug 70 is in contact with the control gate electrode 52.The contact plug 70 is in contact with the control gate wiring 122.

The width of the contact plug 70 in the second direction is smaller thanthe width of the control gate electrode 52 in the second direction.

The control gate wiring 122 intersects with the main gate trench 21.

In the IGBT 200 in the second embodiment, a ring-like trench is formedby the control gate trench 22 a, the control gate trench 22 b, and thesecond connection trench 25. Since both end portions of the two controlgate trenches 22 adjacent to each other are connected to each other, theelectric field strength at the end portion of the control gate trench 22is reduced, and the gate insulating breakdown voltage of the IGBT 200 isincreased.

According to the second embodiment, it is possible to reduce theon-resistance of the IGBT and to reduce the switching loss of the IGBT.The degree of freedom in pattern design of the IGBT increases. It ispossible to reduce the chip area of the IGBT. An operation speed of theIGBT is increased. The reliability of the IGBT is improved.

Third Embodiment

A semiconductor device according to a third embodiment is different fromthe semiconductor device in the first embodiment in that the second gateelectrode includes a lead region, and the second wiring is connected tothe lead region. Some of descriptions of contents similar to thecontents in the first embodiment will be omitted below.

The semiconductor device in the third embodiment is an IGBT 300. TheIGBT 300 is a trench gate type IGBT including a gate electrode in atrench formed in a semiconductor layer. The IGBT 300 is capable ofdouble gate driving.

FIG. 13 is a schematic diagram illustrating the semiconductor device inthe third embodiment. FIG. 13 illustrates a positional relation and aconnection relation between the first trench, the second trench, thefirst gate electrode pad, the second gate electrode pad, the firstwiring, and the second wiring.

FIG. 14 is a top view schematically illustrating a portion of thesemiconductor device in the third embodiment. FIG. 15 is across-sectional view schematically illustrating the portion of thesemiconductor device in the third embodiment.

FIGS. 14 and 15 are enlarged view illustrating a region R surrounded bya dotted frame in FIG. 13. The region R is a boundary region between thecell region 101 and the cell end region 102.

FIG. 15 illustrates a cross-section taken long line HH′ in FIG. 14. FIG.14 illustrates a cross-section of the cell region 101 and the cell endregion 102.

The control gate electrode 52 in the IGBT 300 includes a lead region 52a.

The main gate electrode 51 is connected to the main gate wiring 121 atan end portion of the main gate electrode 51 in the first direction. Themain gate electrode 51 is connected to the main gate wiring 121 at anend portion of the main gate electrode 51 in an opposite direction ofthe first direction. The main gate electrode 51 is connected to the maingate wiring 121 at both end portions.

In FIG. 13, black circles on the main gate wiring 121 indicate positionsat which the main gate wiring 121 is connected to the main gateelectrode 51. For example, the main gate wiring 121 is connected to themain gate electrode 51 at a position (third position) Y1 in FIG. 13. Theposition Y1 corresponds to the end portion of the main gate electrode 51in the first direction. For example, the main gate wiring 121 isconnected to the main gate electrode 51 at a position (fourth position)Y2 in FIG. 13. The position Y2 corresponds to the end portion of themain gate electrode 51 in the opposite direction of the first direction.

The main gate wiring 121 is connected to the main gate electrode 51 onboth the sides of the main gate trench 21 in the first direction and theopposite direction of the first direction.

As illustrated in FIG. 15, the main gate electrode 51 in the firstconnection trench 24 includes the lead region 51 a. The lead region 51 ais provided on the first plane P1. The main gate wiring 121 is incontact with the lead region 51 a at the position (third position) Y1.

The control gate electrode 52 is connected to the control gate wiring122 at an end portion of the control gate electrode 52 in the firstdirection. The control gate electrode 52 is connected to the controlgate wiring 122 at an end portion of the control gate electrode 52 inthe opposite direction of the first direction.

In FIG. 13, black circles on the control gate wiring 122 indicatepositions at which the control gate wiring 122 is connected to thecontrol gate electrode 52. The control gate electrode 52 between twomain gate trenches 21 is connected to the control gate wiring 122 at aposition between the two main gate trenches 21.

The control gate wiring 122 is connected to the control gate electrode52 at a position (first position) X1 in FIG. 13, for example. Theposition X1 corresponds to the end portion of the control gate electrode52 in the first direction. The control gate wiring 122 is connected tothe control gate electrode 52 at a position (second position) X2 in FIG.13, for example. The position X2 corresponds to the end portion of thecontrol gate electrode 52 in the opposite direction of the firstdirection.

The control gate wiring 122 is connected to the control gate electrode52 at a position spaced from the control gate trench 22. The controlgate wiring 122 does not intersect with the control gate trench 22.

As illustrated in FIG. 15, the control gate electrode 52 includes thelead region 52 a. The lead region 52 a is provided on the first planeP1. The control gate wiring 122 is connected to the lead region 52 a atthe position (first position) X1.

In the IGBT 300 in the third embodiment, microfabrication is notrequired for processing the connection between the control gate wiring122 and the control gate electrode 52. Thus, it is easy to manufacturethe IGBT 300.

According to the third embodiment, it is possible to reduce theon-resistance of the IGBT and to reduce the switching loss. The degreeof freedom in pattern design of the IGBT increases. It is possible toreduce the chip area of the IGBT. An operation speed of the IGBT isincreased. The reliability of the IGBT is improved. It is easy tomanufacture the IGBT.

Fourth Embodiment

A semiconductor device according to a fourth embodiment is differentfrom the semiconductor device in the second embodiment in that thesecond connection trench is interposed in the second semiconductorregion. Some of descriptions of contents similar to the contents in thefirst embodiment and the third embodiment will be omitted below.

The semiconductor device in the fourth embodiment is an IGBT 400. TheIGBT 400 is a trench gate type IGBT including a gate electrode in atrench formed in a semiconductor layer. The IGBT 400 is capable ofdouble gate driving.

FIG. 16 is a cross-sectional view schematically illustrating a portionof the semiconductor device in the fourth embodiment. FIG. 16 is adiagram corresponding to FIG. 11 in the second embodiment.

FIG. 17 is a cross-sectional view schematically illustrating the portionof the semiconductor device in the fourth embodiment. FIG. 17 is adiagram corresponding to FIG. 12 in the second embodiment.

In the IGBT 400, the deep region 39 is not provided in the semiconductorlayer 10. The base region 34 is provided in the semiconductor layer 10in the cell end region 102.

In the IGBT 400, the first connection trench 24 is interposed in thedrift region 32. In the IGBT 400, the second connection trench 25 isinterposed in the drift region 32.

In the IGBT 400 in the fourth embodiment, forming a deep deep region 39is not required. Thus, it is easy to manufacture the IGBT 400.

According to the fourth embodiment, it is possible to reduce theon-resistance of the IGBT and to reduce the switching loss. The degreeof freedom in pattern design of the IGBT increases. It is possible toreduce the chip area of the IGBT. An operation speed of the IGBT isincreased. The reliability of the IGBT is improved. It is easy tomanufacture the IGBT.

Fifth Embodiment

A semiconductor device according to a fifth embodiment is different fromthe semiconductor device in the first embodiment in that the firstwiring and the first gate electrode are connected to each other with aconductive layer having a material different from the material of thefirst wiring. Some of descriptions of contents similar to the contentsin the first embodiment will be omitted below.

The semiconductor device in the fifth embodiment is an IGBT 500. TheIGBT 500 is a trench gate type IGBT including a gate electrode in atrench formed in a semiconductor layer. The IGBT 500 is capable ofdouble gate driving.

FIG. 18 is a schematic diagram illustrating the semiconductor device inthe fifth embodiment. FIG. 18 illustrates a positional relation and aconnection relation between the first trench, the second trench, thefirst gate electrode pad, the second gate electrode pad, the firstwiring, and the second wiring.

FIG. 19 is a top view schematically illustrating a portion of thesemiconductor device in the fifth embodiment. FIG. 20 is across-sectional view schematically illustrating the portion of thesemiconductor device in the fifth embodiment.

FIGS. 19 and 20 are enlarged view illustrating a region R surrounded bya dotted frame in FIG. 18. The region R is a boundary region between thecell region 101 and the cell end region 102.

FIG. 20 illustrates a cross-section taken long line II′ in FIG. 19. FIG.20 illustrates a cross-section of the cell region 101 and the cell endregion 102.

The IGBT 500 includes a contact plug 71.

The main gate electrode 51 is connected to the main gate wiring 121 atan end portion of the main gate electrode 51 in the first direction. Themain gate electrode 51 is connected to the main gate wiring 121 at anend portion of the main gate electrode 51 in an opposite direction ofthe first direction. The main gate electrode 51 is connected to the maingate wiring 121 at both end portions.

In FIG. 18, black circles on the main gate wiring 121 indicate positionsat which the main gate wiring 121 is connected to the main gateelectrode 51. For example, the main gate wiring 121 is connected to themain gate electrode 51 at a position (third position) Y1 in FIG. 18. Theposition Y1 corresponds to the end portion of the main gate electrode 51in the first direction. The position Y1 is a position at which the firstconnection trench 24 intersects with the main gate wiring 121.

For example, the main gate wiring 121 is connected to the main gateelectrode 51 at a position (fourth position) Y2 in FIG. 18. The positionY2 corresponds to the end portion of the main gate electrode 51 in theopposite direction of the first direction. The position Y2 is a positionat which the first connection trench 24 intersects with the main gatewiring 121.

The main gate wiring 121 is connected to the main gate electrode 51 onboth the sides of the main gate trench 21 in the first direction and theopposite direction of the first direction.

As illustrated in FIG. 20, the main gate wiring 121 is connected to themain gate electrode 51 in the first connection trench 24 by using thecontact plug 71. For example, the contact plug 71 is formed by burying ahole provided in the interlayer insulating layer 60 on the main gateelectrode 51.

The material of the contact plug 71 is different from the material ofthe main gate wiring 121. As the material of the contact plug 71, amaterial having burying ability for a small hole better than thematerial of the main gate wiring 121 is used. For example, the materialof the main gate wiring 121 is an aluminum alloy, and the material ofthe contact plug 71 is tungsten.

The contact plug 71 is in contact with the main gate electrode 51. Thecontact plug 71 is in contact with the main gate wiring 121.

The width of the contact plug 71 in the first direction is smaller thanthe width of the main gate electrode 51 in the first direction.

The control gate electrode 52 is connected to the control gate wiring122 at an end portion of the control gate electrode 52 in the firstdirection. The control gate electrode 52 is connected to the controlgate wiring 122 at an end portion of the control gate electrode 52 inthe opposite direction of the first direction.

In FIG. 18, black circles on the control gate wiring 122 indicatepositions at which the control gate wiring 122 is connected to thecontrol gate electrode 52. The control gate electrode 52 in the controlgate trench 22 between two main gate trenches 21 is connected to thecontrol gate wiring 122 at a position between the two main gate trenches21.

The control gate wiring 122 is connected to the control gate electrode52 at a position (first position) X1 in FIG. 18, for example. Theposition X1 corresponds to the end portion of the control gate electrode52 in the first direction. The control gate wiring 122 is connected tothe control gate electrode 52 at a position (second position) X2 in FIG.18, for example. The position X2 corresponds to the end portion of thecontrol gate electrode 52 in the opposite direction of the firstdirection.

As illustrated in FIG. 19, for example, the control gate electrode 52 inthe control gate trench 22 a is connected to the control gate wiring 122at the position X1 between the main gate trench 21 a and the main gatetrench 21 b. The position X1 is a position at which the control gatewiring 122 intersects with the control gate trench 22 a.

As illustrated in FIG. 20, the control gate wiring 122 is connected tothe control gate electrode 52 in the control gate trench 22 a by usingthe contact plug 70. For example, the contact plug 70 is formed byburying a hole provided in the interlayer insulating layer 60 on thecontrol gate electrode 52.

The material of the contact plug 70 is different from the material ofthe control gate wiring 122, for example. As the material of the contactplug 70, a material having burying ability for a small hole better thanthe material of the control gate wiring 122 is used. For example, thematerial of the control gate wiring 122 is an aluminum alloy, and thematerial of the contact plug 70 is tungsten.

The contact plug 70 is in contact with the control gate electrode 52.The contact plug 70 is in contact with the control gate wiring 122.

The width of the contact plug 70 in the second direction is smaller thanthe width of the control gate electrode 52 in the second direction.

In the IGBT 500 in the fifth embodiment, the contact plug 71 is used forthe connection between the main gate wiring 121 and the main gateelectrode 51. Thus, it is possible to reduce the area required for theconnection between the main gate wiring 121 and the main gate electrode51. Accordingly, it is possible to reduce a chip area of the IGBT 500.

According to the fifth embodiment, it is possible to reduce theon-resistance of the IGBT and to reduce the switching loss. The degreeof freedom in pattern design of the IGBT increases. It is possible toreduce the chip area of the IGBT. An operation speed of the IGBT isincreased. The reliability of the IGBT is improved. It is easy tomanufacture the IGBT.

In the first to fifth embodiments, a case where the semiconductor layeris made of single crystal silicon is described as an example. However,the material of the semiconductor layer is not limited to single crystalsilicon. For example, other single crystal semiconductors such as singlecrystal silicon carbide may be provided.

In the first to fifth embodiments, a case where the first conductivetype is the p-type, and the second conductive type is the n-type isdescribed as an example. However, the first conductive type may be setto the n-type, and the second conductive type may be set to the p-type.When the first conductive type is set to the n-type, and the secondconductive type is set to the p-type, for example, the second voltage(V2) is the positive voltage.

The arrangement and the ratio of the main gate trench 21, the controlgate trench 22, and the dummy gate trench 23 are not limited to thearrangement and the ratio in the first to fifth embodiments.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the semiconductor device and thesemiconductor circuit described herein may be embodied in a variety ofother forms; furthermore, various omissions, substitutions and changesin the form of the devices and methods described herein may be madewithout departing from the spirit of the inventions. The accompanyingclaims and their equivalents are intended to cover such forms ormodifications as would fall within the scope and spirit of theinventions.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor layer including a first plane and a second plane, thefirst plane being parallel to a first direction and a second directionperpendicular to the first direction, and the second plane facing thefirst plane, and the semiconductor layer including a first semiconductorregion having a first conductive type, a second semiconductor regionhaving a second conductive type and being provided between the firstsemiconductor region and the first plane, a third semiconductor regionhaving the first conductive type and being provided between the secondsemiconductor region and the first plane, a fourth semiconductor regionhaving the second conductive type and being provided between the thirdsemiconductor region and the first plane, a plurality of first trenchesextending in the first direction, being repetitively disposed in thesecond direction, and having a distance from the second plane, thedistance being smaller than a distance from the second plane to thethird semiconductor region, and a plurality of second trenches extendingin the first direction, being repetitively disposed in the seconddirection, and having a distance from the second plane, the distancebeing smaller than a distance from the second plane to the thirdsemiconductor region; a first gate electrode provided in each of thefirst trenches; a first gate insulating film provided between the firstgate electrode and the third semiconductor region and between the firstgate electrode and the fourth semiconductor region, the first gateinsulating film being in contact with the fourth semiconductor region; asecond gate electrode provided in each of the second trenches; a secondgate insulating film provided between the second gate electrode and thethird semiconductor region; a first electrode provided on the firstplane side of the semiconductor layer, the first electrode beingelectrically connected to the fourth semiconductor region; a secondelectrode provided on the second plane side of the semiconductor layer,the second electrode being electrically connected to the firstsemiconductor region; a first gate electrode pad provided on the firstplane side of the semiconductor layer, a first gate voltage beingapplied to the first gate electrode pad; a second gate electrode padprovided on the first plane side of the semiconductor layer, a secondgate voltage being applied to the second gate electrode pad; a firstwiring electrically connecting the first gate electrode pad and thefirst gate electrode; and a second wiring electrically connecting thesecond gate electrode pad and the second gate electrode, wherein thesemiconductor layer includes a first connection trench, two of the firsttrenches adjacent to each other are connected to each other at endportions by the first connection trench, and the second gate electrodein at least one of the second trenches is electrically connected to thesecond wiring at a first position.
 2. The semiconductor device accordingto claim 1, wherein the first position is an end portion of the secondgate electrode in the at least one of the second trenches in the firstdirection.
 3. The semiconductor device according to claim 2, wherein thesecond gate electrode in the at least one of the second trenches iselectrically connected to the second wiring at a second position beingan end portion in an opposite direction of the first direction.
 4. Thesemiconductor device according to claim 1, wherein the first position isa position at which the second wiring intersects with the at least oneof the second trenches.
 5. The semiconductor device according to claim1, wherein the first gate electrode is electrically connected to thefirst wiring at a third position being an end portion in the firstdirection.
 6. The semiconductor device according to claim 5, wherein thefirst gate electrode is electrically connected to the first wiring at afourth position being an end portion in an opposite direction of thefirst direction.
 7. The semiconductor device according to claim 1,wherein the second wiring and the second gate electrode are connectedwith a conductive layer having a material different from a material ofthe second wiring.
 8. The semiconductor device according to claim 7,wherein a width of the conductive layer in the second direction issmaller than a width of the second gate electrode in the seconddirection.
 9. The semiconductor device according to claim 1, wherein thesemiconductor layer includes a second connection trench, and the atleast one of the second trenches and another one of second trenchesadjacent to the at least one of the second trenches are connected toeach other at end portions by the second connection trench.
 10. Thesemiconductor device according to claim 9, wherein the second connectiontrench is interposed in the second semiconductor region.
 11. Thesemiconductor device according to claim 1, wherein a ratio of the numberof the second trenches to the number of the first trenches in a firstregion and a second region located in the second direction of the firstregion is greater than the ratio in a third region interposed betweenthe first region and the second region.
 12. The semiconductor deviceaccording to claim 1, wherein the second wiring intersects with thefirst trenches.
 13. The semiconductor device according to claim 1,wherein the semiconductor layer includes a fifth semiconductor region ofthe first conductive type between the first connection trench and thesecond semiconductor region.
 14. The semiconductor device according toclaim 13, wherein the fifth semiconductor region is provided between thefirst position and the second semiconductor region.
 15. A semiconductorcircuit comprising: the semiconductor device according to claim 1; and acontrol circuit configured to drive the semiconductor device and tochange the second gate voltage from a first voltage to a second voltagebefore the first gate voltage is changed from a turn-on voltage to aturn-off voltage, the second voltage being a negative voltage when thefirst conductive type is a p-type and being a positive voltage when thefirst conductive type is an n-type.
 16. The semiconductor deviceaccording to claim 1, wherein the first position is a position betweentwo of the first trenches adjacent to each other.
 17. A semiconductordevice comprising: a semiconductor layer including a first plane and asecond plane, the first plane being parallel to a first direction and asecond direction perpendicular to the first direction, and the secondplane facing the first plane, and the semiconductor layer including afirst semiconductor region having a first conductive type, a secondsemiconductor region having a second conductive type and being providedbetween the first semiconductor region and the first plane, a thirdsemiconductor region having the first conductive type and being providedbetween the second semiconductor region and the first plane, a fourthsemiconductor region having the second conductive type and beingprovided between the third semiconductor region and the first plane, aplurality of first trenches extending in the first direction, beingrepetitively disposed in the second direction, and having a distancefrom the second plane, the distance being smaller than a distance fromthe second plane to the third semiconductor region, and a plurality ofsecond trenches extending in the first direction, being repetitivelydisposed in the second direction, and having a distance from the secondplane, the distance being smaller than a distance from the second planeto the third semiconductor region; a first gate electrode provided ineach of the first trenches; a first gate insulating film providedbetween the first gate electrode and the third semiconductor region andbetween the first gate electrode and the fourth semiconductor region,the first gate insulating film being in contact with the fourthsemiconductor region; a second gate electrode provided in each of thesecond trenches; a second gate insulating film provided between thesecond gate electrode and the third semiconductor region; a firstelectrode provided on the first plane side of the semiconductor layer,the first electrode being electrically connected to the fourthsemiconductor region; a second electrode provided on the second planeside of the semiconductor layer, the second electrode being electricallyconnected to the first semiconductor region; a first gate electrode padprovided on the first plane side of the semiconductor layer, a firstgate voltage being applied to the first gate electrode pad; a secondgate electrode pad provided on the first plane side of the semiconductorlayer, a second gate voltage being applied to the second gate electrodepad; a first wiring electrically connecting the first gate electrode padand the first gate electrode; and a second wiring electricallyconnecting the second gate electrode pad and the second gate electrode,wherein a ratio of a number of the second trenches to a number of thefirst trenches in a first region is larger than a ratio of a number ofthe second trenches to a number of first trenches in a third region, aratio of a number of the second trenches to a number of the firsttrenches in a second region is larger than the ratio of a number of thesecond trenches to a number of first trenches in the third region, andthe third region is interposed between the first region and the secondregion in the second direction.